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Minimizing Cancer Risk Using Molecular Techniques: a ReviewImmunosciences Lab, Incorporated Beverly Hills, California, Department of Medicine, Drew University School of Medicine and Science Los Angeles, California
Department of Otolaryngology Drew University of Medicine and Science Los Angeles, California
Immunosciences Lab, Incorporated Beverly Hills, California This review article summarizes molecular markers that can signal enhanced risk of cancer and provide clinicians with these clues in order to attempt the use of natural and synthetic compounds to intervene in the early precancerous stages of carcinogenesis before invasive disease begins. With an aim such as this in mind, we have begun to apply molecular techniques based on many research articles to look for biomarkers capable of signaling a greater risk of cancer. It is possible to attain relatively quick answers by monitoring selected signs and damage in the body which provide the environment for abnormal cell growth and differentiation. These molecular techniques aim to uncover critical precancerous events taking place inside the body and identify measurable biologic flags signaling their occurrence. For years now, scientists have understood that the onset of cancer is a gradual, step wise process that may unfold over the course of decades, rather than a single, fixed event that can be dated in a pathologist's report. Carcinogenesis usually encompasses the prolonged accumulation of injuries at several different biological levels and includes both genetic and biochemical changes in cells. At each of these levels there is an opportunity for intervention—a chance to prevent, slow or even halt the gradual march of healthy cells toward malignancy. It is estimated that 75% of cancers are induced by chemicals; thus, if exposure to chemicals is avoided, cancer can be prevented. Also, depending on the individual's genetic background, the ability to metabolize chemicals is different among the population. This means that, "you and I can be exposed to exactly the same amount of a chemical, " yet our response will differ because we metabolize carcinogens differently due to different rates of deoxyribonucleic acid (DNA) repair, apoptosis, and mitosis or different levels of Phase I and Phase II detoxification enzymes. This, along with a more or less efficient immune system, may promote tumor formation or destroy a cancer cell at its earliest stage of development. Therefore, measurement of the biologic markers such as DNA and protein adducts, DNA damage, programmed cell death, DNA repair system, mitosis, gene activation, levels of antioxidants and efficient immune function described in this chapter and summarized in Figures 2 and 10, are biological clues indicating that the body has been assaulted by toxic (or cancer-causing) agents. This early identification of biomarkers for special vulnerability to the effects of chemicals and detection of selected signs of precancerous damage in the body may culminate preventive measures and the saving of lives.
Key Words: 2. Abbreviations: AFB aflatoxin B1 AhR Ah receptor AIDS acquired immune deficiency syndrome ATP adenosine triphosphate BPDE benzo(a)pyrene CDKs cyclin-dependent kinases CFIDS chronic fatigue immune dysfunction syndrome CFS chronic fatigue syndrome CYP1A1 cytochrome P450-1A1 CYP2D6 cytochrome P2D6 F-dUTP flourescent-tagged deoxyuridine triphosphate nucleotides Gx gap phase-x GSTs glutathione S-transferases HIV human immunodeficiency syndrome M mitosis phase MPP+ 1-methyl-4-phenylpyridinium ion MPTP 1-methyl-4-phenyl-1,2,3,6-tetra hydropyridine NAT N- Acetyltransferase NF-kB nuclear factor k B NK natural killer cell PAH polycyclic aromatic hydrocarbon PBLs peripheral blood lymphocytes PCBs coplanar biphenals PCDDs polychlorinated dibenzo-p-dioxins PCDFs dibenzofurans PCR polymerase chain reaction PI propidium iodide PKC protein kinase C ppt parts per trillion pRB powerful growth-inhibitory protein molecule PS phosphotidylserine R restriction point RT reverse transcription RT-PCR reverse transcriptase polymerase chain reaction S DNA synthesis phase TCDD tetra-chlorodibenzo-p-dioxin TdT deoxynucleotidyl transferase tSBO trans-stilbene oxide WBCs white blood cells.
Toxicology and Industrial Health, Vol. 13, No. 5,
589-626 (1997) |
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